This invention relates to a small TIG-arc welding torch.
A typical one of conventional small TIG-arc torches is shown in FIGS. 3a and 3b. Referring to FIGS. 3a and 3b, the small TIG-arc welding torch shown includes a torch body 1, an electrode holder 2 screwed into the torch body 1 and having a collet 3 for securing an electrode 4 in position on the electrode holder 3a by means of a cap 5 screwed into the electrode holder 2, and an O ring 6 for preventing shield gas from leaking from between threaded engaging portions of the electrode holder 2 and the cap 5. The small TIG-arc welding torch further includes a nipple 7 for supplying to the torch body 1 a welding electric current supplied thereto from a welding power supply (not shown) by way of a cable 8 and for supplying to the interior of the torch body 1 shield gas supplied thereto passing through a gap between a hose 9 and the cable 8. The cable 8 is secured to the nipple 7.
Shield gas supplied to the torch body 1 passes through holes 2a formed in the electrode holder 2 and flows into a spacing provided at the center of the electrode holder 2 and is then discharged outwardly of the electrode holder 2 through other holes 2b formed in the electrode holder 2. Shield gas thus discharged outwardly of the electrode holder 2 is moderated in flowing velocity by a gas lens 10 and then rectified by a nozzle 11 and is then discharged outwardly of the torch body 1 to protect the electrode 4 red-heated for welding and a welding area around it from the open air. The small TIG-arc welding torch further includes an insulating plate 12 for insulating the torch body 1 from a welding jig or tool (not shown) and a screw 13 for securely fixing the torch body 1 to the insulating plate 12.
Conventionally, a welding operation is conducted using a small TIG-arc welding machine having such a construction as described above.
However, in such a small TIG-arc welding torch as described above, a metal element which constitutes the torch body is exposed as seen in FIG. 3a. Consequently, if the torch body is brought into contact with or is positioned near an object for welding or an electric conductor which has a higher potential than a welding electric current supplied to the torch body, an arc may appear between the torch body and the object for welding or the conductor and thus damage the torch body. Accordingly, it is difficult to apply the conventional small TIG-arc welding torch for welding of a narrow portion below 20 mm or so.